Abstract.

We have demonstrated and modeled a simple and efficient method to transfer atoms from a first Magneto-Optical Trap (MOT) to a second one. Two independent setups, with cesium and rubidium atoms respectively, have shown that a high power and slightly diverging laser beam optimizes the transfer between the two traps when its frequency is red-detuned from the atomic transition. This pushing laser extracts a continuous beam of slow and cold atoms out of the first MOT and also provides a guiding to the second one through the dipolar force. In order to optimize the transfer efficiency, the dependence of the atomic flux on the pushing laser parameters (power, detuning, divergence and waist) is investigated. The atomic flux is found to be proportional to the first MOT loading rate. Experimentally, the transfer efficiency reaches 70%, corresponding to a transfer rate up to 2.7×108 atoms/s with a final velocity of 5.5 m/s. We present a simple analysis of the atomic motion inside the pushing–guiding laser, in good agreement with the experimental data.

This population ratio may be adjusted by using an elliptically polarized laser beam. It may be a way to optimize experimentally the final atomic beam velocity. In the model, we restrict ourselves to a linear polarization for sake of simplicity
Google Scholar

In this model, we have neglected the heating term related to the fluctuations of the guiding force when the atom jumps between the two hyperfine states. However, this contribution is smaller by about a factor \(\left[\lambda \delta/(2 \pi w \Gamma)\right]^2\) than the spontaneous scattering term, that is more than two orders of magnitude everywhere along the guide
Google Scholar